An organic electroluminescent device can be driven at a low voltage to provide highly bright luminescence, and hence research and development thereon has actively been made. The organic electroluminescent device has an organic layer sandwiched between a pair of electrodes, wherein an electron injected from the cathode and a hole injected from the anode recombine to generate an exciton, the energy of exciton being utilized for luminescence.
In recent years, luminescence efficiency of the device has been increased by using a phosphorescent material. As light-emitting materials, there have been known iridium complexes or platinum complexes (see, for example, U.S. Pat. No. 6,303,238 and WO 00/57676 pamphlet). However, there have not been developed an element that can show both a high luminescent efficiency and a high durability. Thus, development of a light-emitting material (preferably a phosphorescent material) that can show both a high luminescent efficiency and a high durability has been desired.